1. Field of the Invention
This invention relates, in general, to current ramp generators and more particularly to a circuit included in a bubble memory system that determines the fall time of a bubble generate waveform.
2. Background Art
Bubble memory systems normally include a control amplifier that produces a bubble generate waveform that, through additional circuitry, produces a magnetic bubble for storing information. In order to ensure that a bubble is produced, the waveform must meet specific criteria relating to duration and fall time. The fall time may typically be defined as that portion of the waveform from a point which is 90% of the peak amplitude to a point which is 10% of the peak amplitude.
Known bubble memory systems usually shape the bubble generate waveform by having external resistors and capacitors at the generate output. Waveshaping techniques in other applications have typically used complex circuits having a relatively large number of components wherein the components interact to shape the wave. However, these methods result in inefficiencies due to higher cost and larger space requirements.
Thus, what is needed is a current ramp generator that controls the fall time of the bubble generate waveform without external components.